Abstract. Zoonotic Leishmania major causes human disease in similar arid regions in many countries including Israel. The general aim is to study the staple, plant-derived diets of the vector Phlebotomus papatasi and their effects on the vector competence of the sandflies in different habitats. The project comprises the following studies. Evaluation of the scarcity or abundance of plant-derived food sources in various study sites by the identification of plants on which the sandflies feed and by the relative quantities of sugars, or plant tissue residues in sandfly guts. Determination of the chronological age of sandflies from the same sites and the proportions of mature L. major infections they carry. The life span of sandflies is presumably shortened and the risk of human infection is decreased when rich food sources are not found in the local vegetation. The ingested tissues of some plant species, commonly fed upon by the sandflies (including Ricinus communis), kill and agglutinate L. major parasites in infected flies. Plants with this property among the species which are fed upon by sandflies in nature, will be identified; their prevalence in the different study sites will be assessed and their effects on the L. major infections in field caught flies will be scored. An extension of the above studies are the preliminary experiments aimed to assess the potential of using plants for the control of leishmaniasis. These include the selection of suitable domestic plant species and the spray of R. communis extract, which is expected to kill L. major parasites in sandflies, in the sprayed site.